An innovative two-dimensional (2D) grating was designed for precision pitch
measurement using an atomic force microscope with laser interferometers (DLI-AFM). Two kinds of
2D gratings, cylindrical and octagonal pattern, were investigated and compared. In pitch analyses of
these patterns, the latter octagonal pattern showed smaller fluctuation of pitch values, less than 0.1 nm.
Therefore, one of the major uncertainty components, filtering parameter, was reduced dramatically.
We propose the octagonal pattern is probably the most preferable pattern for accurate calibration on
2D gratings.